This invention relates generally to inkjet printers. More specifically, the present invention relates, to a technique for managing the spitting of printhead nozzles in an auxiliary spittoon to maximize print quality or throughput based upon selected preferences.
FIG. 1 illustrates a conventional large format inkjet printer 110 having a pair of legs 114, left and right sides 116, 118, and a cover 122. The printer 110 includes a carriage 100 supporting a plurality of printheads 102-108. The carriage 100 is coupled to a slide rod 124 with a coupling 125. As is generally known to those of ordinary skill in the art, during a printing operation, the carriage 100 travels along the slide rod 124 generally in a Y-axis direction 103 to make a printing pass, typically from the right side 118 to the left side 116 of the printer 110. In addition, as the carriage 100 travels along the Y-axis 103, certain of the printheads 102-108 drop ink onto a medium 130, e.g., paper, through a plurality of nozzles (not shown).
Typically, the medium 130 travels in an X-axis direction 101 at certain times during the printing operation. By virtue of performing a plurality of printing passes over the medium 130 by the carriage 100 in the above-described manner, an image, e.g, plot, text, and the like, may be printed onto the medium.
Also illustrated in FIG. 1 is a printer control panel 120 located on a right side 118 of the large format inkjet printer 110. The printer control panel 120 typically functions as an interface between a user and the printer 110 to enable certain printer operations to be set (e.g., medium advance, printmode, etc.). In addition to housing the printer control panel 120, the right side 18 of the printer 110 typically also houses printer components for performing printing operations (e.g., printer electronics, a service station for servicing operations on the printheads 102-108, etc.).
In performing printing operations with inkjet printers, it is generally known that the print quality and the throughput, i.e., amount of time required to print a plot, may be inversely related. That is, to increase throughput, the print quality is oftentimes sacrificed, or vice versa. To maintain a preferred level of print quality, servicing operations are typically performed on the printheads 102-108. In this respect, although not shown in FIG. 1, inkjet printers typically possess a service station located (xe2x80x9cmain spittoonxe2x80x9d) to perform the above-described servicing operations on the printheads 102-108. Additionally, although not shown in FIG. 1, large format inkjet printers have also been known to possess a second service station (xe2x80x9cauxiliary spittoonxe2x80x9d).
The auxiliary spittoon may be provided to perform servicing operations on the printheads 102-108 in addition to those performed by the main spittoon. In addition, auxiliary spittoons may provide at least one specialized function, e.g., the application of primer on the printheads. Moreover, auxiliary spittoons may be provided in situations where the printer architecture calls for certain servicing operations to be performed in the auxiliary spittoons. For example, the auxiliary spittoon is oftentimes provided when the main spittoon has insufficient volume to contain ink spitted from the printheads. In addition, auxiliary spittoons may be utilized as part of a servicing routine before or after printing a page, during the printing process, and for specific servicing treatments, e.g., recoveries, cleaning, new printhead installation, etc.
There are generally two ways in which the nozzles of the printheads 102-108 may be xe2x80x9crefreshedxe2x80x9d, i.e., cleaned. The nozzles may be refreshed by firing ink drops onto the medium 130, i.e., printing, or by spitting ink drops into the main spittoon. Thus, those nozzles of the printheads 102-108 that actively drop ink onto the medium typically are not required to spit into the main spittoon during various printing passes.
If it is preferred to increase throughput, the number of servicing operations performed on the printheads 102-108 may be reduced. In this respect, the length of time between the servicing operations may also be increased. One problem associated with increasing the length of time between servicing operations is that the properties of fired ink drops may deteriorate, thereby compromising the print quality. For example, ink in position to be fired from the nozzle may become dried and thus not fired through the nozzle. This effect is generally referred to as xe2x80x9cdecapxe2x80x9d and typically occurs when a maximum amount of time a nozzle may be idle (i.e., not firing or spitting ink drops) before an ink drop may be ejected from that nozzle is exceeded. In addition, xe2x80x9cslewing decapxe2x80x9d generally refers to the maximum amount of time a nozzle may be idle during a pass across a medium. Moreover, because the nozzles are moving, the effects of xe2x80x9cslewing decapxe2x80x9d on the nozzles are typically worse than xe2x80x9cdecapxe2x80x9d. As a consequence, slewing decap times are generally shorter than decap times.
To relatively reduce the negative effects of decap, the main spittoons typically perform servicing operations on the printheads as well as capping the nozzles when the printheads are idle for a certain period of time. For example, the printheads typically spit ink into the main spittoons at various times during a printing operation to substantially prevent the occurrence of decap. Additionally, the main spittoons may also include a mechanism for wiping the nozzles of the printheads at various times to generally attempt to wipe off ink dried in the nozzles. Although the performance of the above-stated servicing operations on the printheads has been found to relatively increase the life of the printheads as well as the quality of the printed image, one disadvantage of performing a relatively large number of servicing operations is that the throughput may become compromised.
In performing bi-directional printing operations, especially when the printmode is set for the printheads to perform a left to right sweep, the inverse relationship between print quality and throughput is more evident. In one respect, because the main spittoon is typically not utilized to perform the servicing operations of the main spittoon, if the width of the plot is relatively small, i.e., letter size, A4, etc., the printheads must travel the full length of the printer for the servicing operations on the printheads to be performed, thus decreasing throughput. Otherwise, if the servicing operations are more sparsely performed, then the print quality may be adversely affected.
In those situations where throughput is not relatively important, e.g., during printhead replacement, printhead recovery, etc., the amount of time required to perform these functions is not necessarily critical and thus the amount of time required to use the main spittoon is not relatively detrimental. However, in those instances where throughput is a relatively important factor, and the auxiliary spittoon must be utilized, e.g., the geometry and configuration of the main spittoon is configured for normal spitting but is unable to contain the amount of ink necessary for the certain spitting operation, the carriage must move to the auxiliary spittoon to perform these functions, thereby adversely affecting throughput of the printing operation.
According to one aspect, the present invention pertains to a method for operating a printer having a main spittoon, an auxiliary spittoon, and a printhead. The printhead is operable to perform a uni-directional or bi-directional printing pass. In the method, a selected printmode is received and a decap time is determined in response to the received printmode. Nominal times to complete a uni-directional sweep and a bi-directional sweep are estimated and a last time the printhead was refreshed is determined. A servicing operation is performed in response to the last time the printhead was refreshed exceeding a predetermined value.
According to another aspect, the present invention pertains to an apparatus for operating a printer having a main spittoon, an auxiliary spittoon, and a printhead. The printhead is operable to perform a uni-directional or bi-directional printing pass. The apparatus includes a controller configured to receive a selected printmode and determine a decap time in response to the received printmode. In addition, the controller is further configured to estimate a nominal time to complete a uni-directional sweep and a bi-directional sweep. Furthermore, the controller is configured to determine a last time the printhead was refreshed.
According to yet another aspect, the present invention relates to a method for managing an auxiliary spittoon in a printer having a main spittoon and a printhead. The printhead is operable to perform a uni-directional or bi-directional printing pass. In the method, a selected printmode is received and a decap time is determined in response to the received printmode. Nominal times to complete a uni-directional sweep and a bi-directional sweep are estimated and a last time the printhead was refreshed is determined. In addition, it is determined whether the printing pass is a left to right sweep in response to the printmode being bi-directional and whether a single sweep time exceeds the decap time in response to the printing pass being a left to right sweep. Moreover, a spitting operation of the printhead is performed in the auxiliary spittoon in response to a sum of a current time, e.g., the time since the printer was activated, and the single sweep time minus a last time a spit on the fly was performed is greater than or equal to the decap time and a bi-directional printing pass with the printhead is performed.
According to still another aspect, the present invention relates to a computer readable storage medium on which is embedded one or more computer programs, where the one or more computer programs implement a method for operating a printer having a main spittoon, an auxiliary spittoon, and a printhead. The printhead is operable to perform a uni-directional or bi-directional printing pass. The one or more computer programs includes a set of instructions for receiving a selected printmode, determining a decap time in response to said received printmode, estimating a nominal time to complete a uni-directional sweep and a bi-directional sweep, determining a last time the printhead was refreshed, determining whether the printing pass is a left to right sweep in response to said printmode being bi directional, determining whether a uni-directional sweep time exceeds said decap time in response to the printing pass being a left to right sweep, performing a spitting operation of the printhead in the auxiliary spittoon in response to a sum of a current time, e.g., the time since the printer was activated, and the uni-directional sweep time minus a last time a spit on the fly was performed is greater than or equal to the decap time, and performing a bi-directional printing pass with the printhead.